Systematically Probing the Effect of Microscopic Features on the Sensing Performance of Piezoresistive Pressure Sensors

Flexible and wearable piezoresistive pressure sensors have received tremendous interest for various potential applications in electronic skins, intelligent robotics, healthcare biomonitoring, and artificial intelligence. Sensitivity and linearity are crucial parameters for flexible pressure sensors. Introducing microscopic features is a promising strategy to effectively improve these characteristics. In this paper, we theoretically and experimentally investigate the effect of the microscopic features on the sensitivity of the piezoresistive pressure sensors. For the common micropyramid feature, we find that sensitivity is directly proportional to the height and inversely proportional to the angle, which is ascribed to the more concentrated stress imposed on the sharper area, in turn contributing to a relatively large change in the contact area (( A – A 0 )/ A 0 ). Theoretical analysis shows good agreement with the experimental observation. By tailoring the height, the proposed PDMS-based flexible pressure sensor achieves an ultrahigh sensitivity (249.41 kPa –1 ) and exhibits a minimum detection limit of 0.306 Pa. In addition, the pressure sensor with a microcylinder feature possesses a comparatively high sensitivity among five different microscopic features. We also designed and demonstrated that the pressure sensor with a microcylinder-based bark structure could offer a higher sensitivity and larger linearity regime, thanks to the quick increment of touchpoints and more variation stages with loads. Our results are useful in understanding the effect of the microscopic features and can be taken as a reference in the design of high-performance pressure sensors.